Distinguishing bipolar disorder from unipolar depression in general practice: A systematic review

Bipolar disorder affects approximately 1% of the population, although some studies report prevalence rates of up to 6%. Distinguishing it from unipolar depression remains challenging, with diagnostic delays often exceeding ten years. This systematic review aims to identify clinical and historical features of depressive episodes that support the earlier detection of bipolar disorder in general practice.

A systematic review was conducted in accordance with PRISMA guidelines. The PubMed database was searched using MeSH terms. Study quality was assessed using the Newcastle-Ottawa Scale and the PRISMA checklist.

Of the 525 articles identified, 36 met the inclusion criteria. Early age at onset, recurrent episodes, family history of bipolar disorder, cyclothymic temperament, suicide attempts, postpartum depression, psychotic features and mixed episodes emerged as the most consistently associated indicators of bipolar disorder. Other clinical characteristics showed more heterogeneous or limited associations. Although individual features lack sufficient predictive value when considered in isolation, their combined presence may enhance clinical suspicion and facilitate earlier identification of bipolar disorder in primary care settings.

This review identified a combination of clinical and historical features of depressive episodes that help distinguish between bipolar disorder and unipolar depression in general practice. Identifying these features through a structured clinical interview, as a complement to existing screening tools such as the Mood Disorder Questionnaire, may help reduce diagnostic delays and improve outcomes.